Fall back to ffmpeg when Go's JPEG decoder rejects a source

Go's stdlib image/jpeg refuses some valid-but-rare features such as
4:1:1 luma/chroma subsampling (ANN's CDN serves these). When the
in-process decode fails, route the bytes through ffmpeg the same way
we already do for video sources.

internal/web/static/css/input.css

@@ -44,6 +44,20 @@ html[data-phase="night"] {
 @layer base {
   body { font-family: "Nunito", system-ui, sans-serif; }
   html { scroll-behavior: smooth; }
+  /* Belt-and-braces: never let stray wide content push horizontal scroll on
+     the whole page (the channel nav scrolls inside itself instead). */
+  html, body { overflow-x: hidden; }
+}
+
+@layer components {
+  /* Channel pill row may exceed viewport on mobile once enough channels are
+     configured. Let it scroll inside its own rounded container and hide the
+     scrollbar chrome so it still reads as a clean pill. */
+  .pete-channel-nav {
+    scrollbar-width: none;
+    -ms-overflow-style: none;
+  }
+  .pete-channel-nav::-webkit-scrollbar { display: none; }
 }
 
 @layer utilities {

internal/web/templates/layout.html

@@ -32,16 +32,16 @@
   <canvas id="pete-weather" class="pointer-events-none fixed inset-0 -z-[5] h-full w-full" aria-hidden="true"></canvas>
 
   <header class="mx-auto max-w-6xl px-4 pt-8 pb-4 sm:pt-12">
-    <div class="flex items-center justify-between gap-4">
+    <div class="flex flex-wrap items-center justify-between gap-3 sm:gap-4">
-      <a href="/" class="flex items-center gap-3 group">
+      <a href="/" class="flex items-center gap-3 group min-w-0">
         <img src="/static/img/pete.avif" alt="Pete" width="48" height="48"
-             class="h-12 w-12 rounded-2xl bg-[color:var(--card)] shadow-pete border-2 border-[color:var(--ink)]/10 object-cover group-hover:-rotate-6 transition-transform">
+             class="h-12 w-12 shrink-0 rounded-2xl bg-[color:var(--card)] shadow-pete border-2 border-[color:var(--ink)]/10 object-cover group-hover:-rotate-6 transition-transform">
         <span class="font-display text-3xl font-bold tracking-tight">{{.SiteTitle}}</span>
         <span class="hidden sm:inline rounded-full bg-[color:var(--accent)]/20 px-3 py-1 text-xs font-semibold uppercase tracking-wider text-[color:var(--ink)]/70" data-phase-label>day</span>
       </a>
-      <div class="flex items-center gap-2">
+      <div class="flex items-center gap-2 min-w-0 max-w-full">
         <button type="button" data-search-trigger title="Search (⌘K)"
-                class="flex items-center gap-2 rounded-full bg-[color:var(--card)] px-3 py-2 text-sm shadow-pete border-2 border-[color:var(--ink)]/10 hover:bg-[color:var(--ink)]/5 transition">
+                class="flex shrink-0 items-center gap-2 rounded-full bg-[color:var(--card)] px-3 py-2 text-sm shadow-pete border-2 border-[color:var(--ink)]/10 hover:bg-[color:var(--ink)]/5 transition">
           <svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"
                stroke-linecap="round" stroke-linejoin="round" class="h-4 w-4 text-[color:var(--ink)]/60">
             <circle cx="11" cy="11" r="7"></circle>
@@ -50,11 +50,11 @@
           <span class="hidden sm:inline text-[color:var(--ink)]/60 font-semibold">Search</span>
           <kbd class="hidden sm:inline-flex items-center rounded-md bg-[color:var(--ink)]/5 px-1.5 py-0.5 text-[10px] font-mono font-semibold text-[color:var(--ink)]/60">⌘K</kbd>
         </button>
-        <nav class="flex items-center gap-1 sm:gap-2 rounded-full bg-[color:var(--card)] p-1 shadow-pete border-2 border-[color:var(--ink)]/10">
+        <nav class="pete-channel-nav flex min-w-0 items-center gap-1 sm:gap-2 overflow-x-auto rounded-full bg-[color:var(--card)] p-1 shadow-pete border-2 border-[color:var(--ink)]/10">
           {{$active := .Active}}
           {{range .Channels}}
           <a href="/{{.Slug}}"
-             class="rounded-full px-3 py-2 text-sm font-semibold transition
+             class="shrink-0 rounded-full px-3 py-2 text-sm font-semibold transition
                     {{if eq $active .Slug}}bg-theme-{{.Theme}} text-white shadow-sm{{else}}hover:bg-[color:var(--ink)]/5{{end}}">
             <span aria-hidden="true" class="mr-1">{{.Emoji}}</span><span class="hidden sm:inline">{{.Title}}</span>
           </a>

internal/web/thumbs.go

@@ -178,7 +178,7 @@ func buildAvifThumb(src, outPath string) error {
 	}
 
 	if urlIsVideo || isVideoContentType(resp.Header.Get("Content-Type")) {
-		return buildAvifFromVideoFrame(body, outPath)
+		return buildAvifFromFFmpeg(body, outPath)
 	}
 
 	if isAvif(body) {
@@ -195,6 +195,13 @@ func buildAvifThumb(src, outPath string) error {
 	}
 	src2, _, err := image.Decode(bytes.NewReader(body))
 	if err != nil {
+		// Go's stdlib JPEG decoder rejects some valid-but-rare features
+		// (e.g. 4:1:1 luma/chroma subsampling served by ANN's CDN). Hand
+		// the bytes to ffmpeg as a permissive fallback — it produces the
+		// same shape of output as the video path.
+		if ffErr := buildAvifFromFFmpeg(body, outPath); ffErr == nil {
+			return nil
+		}
 		return fmt.Errorf("decode: %w", err)
 	}
 	b := src2.Bounds()
@@ -265,12 +272,13 @@ func isVideoContentType(ct string) bool {
 	return strings.HasPrefix(strings.ToLower(strings.TrimSpace(ct)), "video/")
 }
 
-// buildAvifFromVideoFrame writes the downloaded video to a temp file, asks
+// buildAvifFromFFmpeg writes the downloaded bytes to a temp file, asks
 // ffmpeg to extract a single resized frame as PNG, then hands it to avifenc.
-// ffmpeg is optional — if it's missing we return an error and the caller
+// Used both for video sources and as a permissive fallback for images whose
-// falls back to redirecting to the source URL, just like any other build
+// JPEG features Go's stdlib decoder rejects. ffmpeg is optional — if it's
-// failure.
+// missing we return an error and the caller falls back to redirecting to
-func buildAvifFromVideoFrame(body []byte, outPath string) error {
+// the source URL, just like any other build failure.
+func buildAvifFromFFmpeg(body []byte, outPath string) error {
 	if _, err := exec.LookPath("ffmpeg"); err != nil {
 		return fmt.Errorf("ffmpeg not available: %w", err)
 	}